The present disclosure relates to xerographic printers and photocopying machines. In particular, disclosed herein is a printing system and method for presenting dynamically generated sample pages of a print job to a printing system user.
A typical xerographic document printing system, such as a laser printer, photocopier, or multi-function device, may include a controller module, and a user interface which may have pushbuttons, lighted indicators, or an interactive display device such as a touch screen. A printing system may also include a document processing assembly (i.e., a sheet feeding assembly), an imaging assembly (for transferring an image to a sheet), and a finishing assembly (i.e., a stapler, hole puncher or binder), which function cooperatively to produce printed materials in a wide variety of formats. In a typical xerographic architecture, a printing system may include one or more output trays to which printed sheets can be delivered. In another typical xerographic architecture having a plurality of serially-coupled document finishing assemblies, separate output trays may be provided at each document finishing assembly.
Ease of use, printing speed and high quality images are desirable attributes in printing and photocopying machines. Accordingly, techniques have been developed whereby printing and photocopying machines can sense the operating conditions of the machine, convey information relating to these conditions to the user, and, additionally or alternatively, use information derived from the sensed conditions to modify the machine's operation accordingly.
For example, sensors incorporated within a printing system or photocopier can determine whether the machine's supply of xerographic toner is low, or has been exhausted. In the case where the toner supply is near depletion, for example, when less than 10% of the toner supply is remaining, a printing system may issue a message to the user via a user interface, such as a flat panel display device, alerting the user to the low toner condition. In another scenario, when the toner supply is fully depleted, a printing system may suspend printing operations until the toner is replenished, or a new toner cartridge is installed. In yet another scenario, when the system senses a malfunction, any incorrectly-printed or out of sequence sheets within each document finishing assembly may be purged to a designated output tray, which may be said to be a purge tray.
Other sensors within a printing system can include those which detect when the paper supply is exhausted, the location of a jammed or misfed sheet, or whether an original sheet that is about to be copied or scanned is of a non-standard size. In each instance, the printing system has the ability to sense a particular condition warranting attention, and take appropriate action.
However, certain conditions may arise within a printing system which cannot readily be detected by sensors. For example, normal printing system wear and tear may cause uneven rendering of images on each sheet, such as light or dark areas, which may be objectionable. In another example, a user may inadvertently or unknowingly scratch an imaging surface, such as a photoreceptor belt or drum, while clearing a jam within the printing system. Any scratch on the photoreceptor is likely to cause a corresponding mark on each output sheet. In these and similar instances, the only way to detect such undesirable image defects may be by visual inspection of an actual output page. However, this may be ineffective where large and/or multiple jobs are printed, because many pages may be wastefully printed before the operator notices a problem. Even if the operator is proactive and attempts to inspect the printed pages as they stack in the output trays, the very act of touching those pages as they exit the printer can cause jams and disruption of a print job.
One method by which printing systems have addressed this issue is by providing a “print sample page” function to the user. Typically, this sample page function is used during large print jobs whereby the user requests that a second copy of the page currently being printed be generated and delivered to a separate output tray, such as a top tray or purge tray, of the printing system. In this manner, the operator may visually evaluate the current image quality of the printer using the representative sample page just printed, without disturbing the pages being stacked in the primary output trays.
However, this method may have drawbacks because the operator does not know precisely which page is being printed, or ripped (raster image-processed), at the moment the sample page is requested, so it is nearly impossible to determine with certainty which page of the print job will be actually be sampled. Often, an operator will sample a page only to learn it was unrepresentative of the majority of the pages in the print job, i.e., the sample page may have near zero percent image area coverage (mostly white) or may have near one hundred percent image coverage (mostly black). In these cases the sample page will fail to achieve its intended purpose of providing an operator a way to monitor the ongoing print quality of a print job. As a result, the operator must repeatedly request sample prints and retrieve each page from an output bin for inspection, until a satisfactory page is obtained. This ritual wastes time, media, and other resources.